CVD Diamond vs Moissanite: How to Tell Them Apart

A CVD diamond is a real diamond, grown in a laboratory using Chemical Vapor Deposition. It is carbon, it is chemically and optically identical to a mined diamond, and it is graded on the same scale. Moissanite is a different mineral entirely, silicon carbide, which happens to look similar to the eye. Both are legitimate choices. They are not the same material, and anyone selling them as interchangeable is being careless.

What is a CVD diamond?

CVD stands for Chemical Vapor Deposition. A thin diamond seed is placed in a chamber, carbon-rich gas is introduced, and the gas is energised until carbon atoms settle onto the seed and build a crystal layer by layer. The result is a diamond in every measurable sense: the same carbon lattice, the same hardness of 10 on the Mohs scale, the same refractive index, the same behaviour under light.

The only genuine difference from a mined diamond is where it formed. It is not a simulant, not a substitute and not a coating. Graders assess it on the same 4Cs, and a gemmological laboratory identifies its origin from growth-pattern evidence, not from anything a buyer would ever see.

What is moissanite?

Moissanite is silicon carbide. It occurs naturally in meteorite fragments in quantities far too small to cut, so effectively all jewellery moissanite is lab created. It scores 9.25 on the Mohs scale, which is hard enough for daily wear but measurably softer than diamond.

Its defining optical property is dispersion, the degree to which it splits white light into spectral colours. Moissanite disperses light roughly 2.4 times as strongly as diamond. That is the source of the rainbow flashes people either love or immediately identify as not-diamond, and it is the most reliable way to tell the two apart by eye.

The differences that matter

How can you tell them apart?

By eye, look at the fire in bright directional light. Diamond returns mostly white light with occasional coloured flashes. Moissanite throws noticeably more colour, and in larger sizes that rainbow effect becomes hard to miss. Below about half a carat the difference is genuinely difficult to call without tools.

A jeweller will use a thermal and electrical conductivity tester, because moissanite conducts electricity in a way diamond does not. Older diamond testers that measure heat alone read moissanite as diamond, which is why the combined testers exist. A doubling effect is also visible under magnification in moissanite, because it is doubly refractive where diamond is not.

Which should you choose?

Choose a CVD diamond if you want a diamond. That sounds circular but it is the actual decision. If the fact that it is a diamond matters to you or to the person wearing it, no amount of visual similarity substitutes for that, and resale, insurance and family expectations all follow the material.

Choose moissanite if the appearance and the durability are what you are buying, and you would rather put the budget into size or setting. A moissanite of a given size costs a fraction of a diamond of the same size. For a fashion piece, a travel ring, or a first ring where budget is the binding constraint, that is a sound trade rather than a compromise.

Does a lab grown diamond hold value better?

Neither holds value the way a mined diamond of investment quality might, and it is worth being straight about that. Lab grown diamond prices have fallen steadily as production capacity has grown. Moissanite has always been priced as a manufactured stone. Buy either because you want to wear it, not as an asset.

What a diamond does retain is insurability and recognition. An IGI report on a lab grown diamond describes a specific stone in terms every jeweller and insurer understands, which is why we include IGI certification on centre stones from 1.00 carat upward.

What we sell, and what we do not mix

Ronora sells both, and never in the same piece. A lab grown diamond ring uses CVD diamonds throughout, including the accent stones. A moissanite ring uses moissanite throughout. We do not set moissanite accents around a diamond centre, or the reverse, because a customer who is told a ring is one material should not find the other inside it.

Our diamonds are CVD, cut to Excellent, graded D to F on colour, and set in solid gold or platinum.

Where to start

Read the full lab grown diamond guide for how CVD growth works, or compare the two directly in our diamond types guide. To browse, see lab grown diamond engagement rings or moissanite rings.